Army scientists could use urine to charge 3D printed drones that eat themselves

Oct 2, 2017 | By Benedict

Scientists at the U.S. Army Research Laboratory have discovered that a recently engineered aluminum nano-powder can rapidly produce hydrogen when mixed with urine. The powder could be used to make 3D printed robots that “feed off their own structures” and self-destruct after missions.

ARL's Anthony J. Roberts uses urine to set off a chemical reaction

Back at the end of July, scientists and engineers at the U.S. Army Research Laboratory discovered that a new aluminum nanomaterial could produce high amounts of energy when mixed with water, or with “any liquid containing water.”

The Army team hailed the discovery as a potentially very exciting one. The material, they said, could be used to generate hydrogen for use in fuel cells, thanks to its “mechanism for a rapid and spontaneous hydrolysis of water.”

The nano-galvanic powder doesn’t even require a catalyst to produce the hydrogen.

After that initial discovery, the scientists tried using the aluminum-generated hydrogen to power a radio-controlled tank. Amazingly, the bubbling reaction produced enough power to send the vehicle whizzing around their laboratory.

But what was most exciting (from our point of view) was another potential application for the nanomaterial.

Urine contains more than 3,000 compounds

According to the Army experts, the nanomaterial power could be 3D printed to create “air and ground robots that can feed off of their very structures and self-destruct after mission completion.”

That’s right, 3D printed robots and drones could essentially take little nibbles of themselves by dipping their bodies in water—a process that would decompose their outer shells in order to generate extra power. Later, after a mission is complete, these robots could completely self-destruct by, for example, submerging themselves in a lake.

These potentially self-destructing 3D printed robots sounded very exciting in themselves, but the same Army scientists have just posted a crazy-sounding update to their research.

During recent experiments, the team found that the aluminum nanomaterial actually produces more hydrogen when combined with urine rather than water.

This means the Army eggheads can generate extra charge for their batteries by simply replacing water with pee.

Roberts powers a radio-controlled toy tank with hydrogen

(Images: David McNally)

“When we demonstrated it with urine, we saw almost a factor of twofold increase in the reaction rates,” said Dr. Kristopher Darling, an ARL researcher. “We were very excited. As a group we have been pushing for the last few months on developing the efficiency and the reaction kinetics to try to get them faster.”

The researchers say that a kilo of the powder can produce 220 kilowatts of power in just three minutes.

Interestingly, they aren’t totally sure why the urine is so effective at generating hydrogen, but they suspect it may be something to do with its electrolytes and acidity.

“It's unique because the rate of the reaction is so efficient and extremely rapid from such a small volume of material,” Darling added.

At present, the scientists are trying to work out how their discovery can best be put to practical use in order to benefit soldiers out in the field. First and foremost, the nanomaterial looks like it could be an ideal energy source, especially in situations where sending out energy supplies is dangerous and expensive, but the scientists also want to explore the 3D printing scenario outlined back in July.

“Our basic focus is materials development and optimization," Darling said. "We're looking at how we can optimize the composition [of the nanomaterial], its interactions with other fluids, including saliva and other liquids available to soldiers in a field environment.”

In terms of autonomous 3D printed land and air robots that do not have the luxury of waste-providing soldiers near them, it is slightly harder to see how the process could be deployed with urine, though robots operating near sewage systems could perhaps take a refreshing dip into urine-filled waters in order to get a quick recharge or to self-destruct.

The Army researchers are currently attempting to patent the process.

This isn’t even the first urine 3D printing story we’ve had this year. While soldiers could be charging their equipment with pee in the near future, astronauts could soon be making urine-based 3D printing materials up in space. Whatever next?